The invention concerns a method for applying films to interior wall sections of the bodywork of a vehicle during the course of assembly line production of the vehicle. In addition, the invention relates to a suitable device for execution of said method.
The use of films is known in the construction of vehicles in order to undertake acoustical measures and also for purposes of reinforcement. The acoustical measures include (body) sound-proofing, sound dissipation, sound isolation, sound absorption and sound reflection, etc. Films applied to larger sheet metal sections not only have sound deadening but also stabilizing or reinforcing effects.
The term “film” has acquired a particular meaning in the specialized trade language, independent of its purpose. It involves layer sections which, depending upon the effect to be achieved, may have the most diverse construction (single layer- or multi-layer systems made of different materials, frequently bitumen). The general term “film” is retained in the following.
Films of this kind are employed in many areas of a vehicle. Among them are interior surface sections of                doors (two or four)        side walls (for example with two doors)        wheel cases, in particular wheel cases adjoining the passenger compartment        floor sheet metal pieces (for example two each in front and/or in the rear), also in the trunk        sheet metal walls between engine compartment and passenger compartment        interior side of the roof (overhead),        engine compartment        
Application of films on interior wall sections of vehicles may be impeded by other structures. This applies, for example, with respect to doors, which are as a rule constructed in two-sheet fashion. The side wall of a door case facing the passenger compartment is equipped with openings, through which must be passed the films to be applied to the inner surface of the outer side wall. This process is all the more difficult the smaller the openings in the inner side wall of the door casing or the larger the films are, since the films have adhesive effect, either due to adhesive forces (layer of glue applied on the film) or due to magnetic forces (magnetic material arranged in the film, in particular in form of powders). Applications of films of this type are highly time consuming and their placement is not precise.
Deposition or application of films on interior wall sections of vehicles or vehicle components was originally done by hand. In modern assembly lines frequently ten or more persons were busy applying various respectively delivered films to the designated interior wall sections. In this phase, the car body is still in its raw state, i.e. the car body components have been welded and their surface has been primed. So that the films will adhere up to their final fusion with the respective sheet metal section on vertical areas or in the case of overhead installation, they have, as already mentioned, adhesive properties. For that purpose, they can be equipped on one side with an adhesive layer. Another possibility consists in utilizing films comprising ferro-magnetic additions, which will temporarily adhere to the sheet metal sections based on magnetic forces. Following application of films performed in this manner on the pertinent interior wall sections of the raw bodywork, they are given a coat of lacquer.
As a rule, several coats of lacquer are applied. Subsequently, the car body is passed through an oven in which drying of the lacquer takes place. In addition, due to the thermal effect, final fusion of films with their respective wall section takes place. The thus attained full-surface positioning of the films on their respective base is a required pre-requisite so that the desired effect will definitely be achieved.
It is a drawback with respect to the described method of applying the films by hand on their pertinent sheet metal sections, since creation of dust and in particular of lint is unavoidable. These stick to the surface of the car body, which is subsequently given a coat of lacquer. Consequently the lint caught in the coats of lacquer results in uneven lacquer surfaces. They must be re-worked by grinding, by another coat of lacquer and by drying. In addition, the known method is relatively expensive based on high amount of manual labor.
In order to avoid the described drawbacks, utilization of a robot is known from DE-A1-199 27 105, i.e. an apparatus with a multi-member arm and a movably thereto attached gripping framework. With the aid of the gripping framework, one or several films are taken up outside the car body, after that the film or films together with the gripping framework is/are transported to the deposit site with the aid of the arm through an opening in the car body and deposited there.
Due to the fact that the application of the films is no longer done by hand, a significant source for the creation of dust or lint is eliminated. Time-consuming and costly re-work on the lacquer surfaces is done away with. In addition, placement of the films on the pertinent inner wall sections can take place with significantly greater precision, so that primarily the desired acoustical effect can be achieved more reliably. Finally, utilization of apparatuses executing placement of the films is more cost-effective over the long term.
With respect to the currently popular large dimensioned vehicles having a multitude of windows, frequently also several sliding roofs, and in case of trailers as well as residential trailers, there likewise exists the need to apply a multitude of differently large and individually cut or preformed films onto a corresponding multitude of interior wall sections of the respective vehicle. The gripping framework of the prior known robot must therefore be passed in and out of the car body, even if it can accept several films. This results on the one hand in relatively long installation times. And, on the other hand, the technical requirements with respect to the length and articulation of the rotor arms and the alignment possibilities of the gripping framework are high in order to reach from the outside all sites to be covered with film, in particular the places located relatively high on the interior side of the roof and overhead.